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Synthesis and characterization of TiO2 nanopowders for fabrication of dye sensitized solar cells
Abstract
Titanium dioxide (TiO2) nanopowders were synthesized by sol-gel and refluxing methods, and compared with commercial titanium dioxide (P25). The as-synthesized TiO2 samples were characterized by X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopy, energy dispersive X-ray (EDX) spectroscopy, selected area electron diffraction (SAED), and UV-vis and photoluminescence (PL) spectroscopy. In this research, the as-synthesized samples were used to fabricate dye sensitized solar cells (DSSCs) and found that TiO2 synthesized by sol-gel method has the highest efficiency of VOC = 0.465 V, JSC = 1.361 mA/cm2 and FF = 0.647.
... Plant metabolite materials serve as excellent reducing agents, which include alkaloids, phenolic compounds, and sterols. TiO 2 NPs were synthesized using different methods, such as sol-gel method [9][10][11][12][13][14][15] and hydrothermal method [16,17], microemulsion, sol gel and precipitation method [6], refluxing method [15], laser ablation [18], modified solvothermal method [19], and simple wet chemical method [20]. In addition, TiO 2 NPs were also green synthesized by biological methods using different plant extracts as reducing and stabilizing agents. ...
... Plant metabolite materials serve as excellent reducing agents, which include alkaloids, phenolic compounds, and sterols. TiO 2 NPs were synthesized using different methods, such as sol-gel method [9][10][11][12][13][14][15] and hydrothermal method [16,17], microemulsion, sol gel and precipitation method [6], refluxing method [15], laser ablation [18], modified solvothermal method [19], and simple wet chemical method [20]. In addition, TiO 2 NPs were also green synthesized by biological methods using different plant extracts as reducing and stabilizing agents. ...
Biological synthesis pathway was used to successfully prepare titanium dioxide nanoparticles (TiO2 NPs) as a simple synthetic process, employing three distinct aqueous extracts: pomegranate (Pom), Beta vulgaris (V.B), and Seder. In addition, typical TiO2 NPs were made using a simple wet chemical approach for comparison. Different characterization techniques, such as UV–Vis spectroscopy, XRD, FT-IR, and TEM, were used to examine all of the TiO2 NPs that were generated either through the biologically or chemically route. For all the synthesized samples, the observed XRD results reveal a tetragonal structure with two phases, rutile and anatase. The particle sizes of the materials developed range from 15.2 to 20.6 nm. The obtained results suggested that the nature of plant extract predisposes the altered aspects of the manufactured particles, such as photocatalytic, particle size, and the ratio between two phases. FT-IR spectroscopy validated the biomolecules elaborated in the biosynthetic method. In the presence of UV irradiation, the photocatalytic activities of NPs were studied using Methyl Orange (MO) organic dye as an example of water pollutant. As a result of the lower mass fraction of rutile phase, the green generated TiO2 NPs had greater photocatalytic activity and efficiency in the photodegradation of MO compared to the chemically synthesized TiO2 NPs samples. The photocatalytic destruction of the assembled NPs was discovered to follow pseudo-first order kinetics trend, with efficiency exceeding that of ultraviolet light. Moreover, the obtained results confirmed that the prepared TiO2 NPs based on biological sources are considered as a promising candidate aimed at removal of organic pollutants from water and can be applied in waste water treatment applications.
... Nanopores of 10 nm in TiO 2 were created through the decay of tinplating agents during calcination. TEM images as shown in Fig. 13 show TiO 2 nanoparticles created via a) Sol-gel [109], b) hydrothermal [106], and c) Template method [108]. ...
... A power conversion efficiency of 6.0%, which is about 2.88 times higher than that of bare TiO 2 Fig. 13. TEM illustrations of TiO 2 nanoparticles created via a) Sol-gel [109], b) hydrothermal [106], and c) Template method [108]. ...
Energy demand and its usage are globally increasing day by day. Currently, the sources of global energy are mainly sustained by fossil fuels. However, acquiring energy directly from the fossil fuel is not the most appropriate and sustainable way, because it results in the depletion of natural resources as well as it is also the main cause of CO2 emission. Renewable energy is the most appropriate and sustainable way to fulfill the growing energy demand, which can also be the source of sustainable power generation. Solar energy has sublime environmental advantages as compared to other sources of energy and will not produce any CO2 rich emissions. Photovoltaic cells directly convert solar energy into electrical energy. Dye-sensitized solar cells (DSSCs) are a part of thin-film photovoltaic technology. Because of their low-cost, easy processing, and stability, they are especially suited for wireless sensor networks, electronic signs, computer peripherals, and wearable electronics. The photovoltaic performance of DSSCs depends on the light-harvesting efficiency (LHE), charge transport, charge injection, charge collection, and charge recombination rate. These parameters are affected by type, morphology, composition, and deposition methods of photoanode materials. In this review, all these parameters and their effect on the performance of DSSCs will be discussed in detail. This review will cover the whole aspect of photoanode materials for DSSCs applications.
... Titania in different structural forms is excessively being used due to its exceptional sized characteristics. TiO 2 -based nanostructures are being utilized for unique applications due to their unique energy band gap and quantum efficiency, highlighting their photo-physical, surface, and photo-chemical properties (Phonkhokkong, 2016). ...
... To prepare TiO 2 with the desired properties, different methods have been employed, such as hydrothermal [11], sol-gel [12], electrochemical [13], chemical vapor deposition [14], and hydrolytic precipitation [15,16]. Amongst these methods, the sol-gel has been recognized as the most appropriate and straightforward chemical technique based on its versatility, low processing temperature, low-cost, stability, and high homogeneity [17]. Sol-gel involves the hydrolysis and condensation of the titanium alkoxides in aqueous media to produce different morphologies such as aerogels, wires, tubes, quantum dots, sheets, rods, and nanoparticles. ...
TiO 2 is a wide bandgap semiconductor nanomaterial that has attracted considerable attention for its diverse applications. The structure, crystal size, morphology, and bandgap of TiO 2 play a vital role in photocatalysis and are related to the synthesis conditions and methods. In this study, the nanoparticles were synthesized using the sol-gel method and investigated the effect of varying pH on their structural and opto-electronic properties. The X-ray diffraction patterns revealed anatase phase in all the samples and presence of rutile phase (4wt%) at pH 7. The smallest crystal size was observed at pH 8, while a neutral pH gave larger crystal sizes. The TiO 2 grains were observed to have a nearly spherical spongy-like shape and agglomerated nanoparticles. The bandgap energy was found to increase with the increase pH value until neutral. The photocatalytic activity of the NPs was investigated by the degradation of methylene blue solution. The TiO 2 nanoparticles obtained at a pH of 8 exhibited the highest degradation efficiency of 82 % at a degradation rate of 0.0048/min.
... To prepare TiO 2 with the desired properties, different methods have been employed, such as hydrothermal [11], sol-gel [12], electrochemical [13], chemical vapor deposition [14], and hydrolytic precipitation [15,16]. Amongst these methods, the sol-gel has been recognized as the most appropriate and straightforward chemical technique based on its versatility, low processing temperature, low-cost, stability, and high homogeneity [17]. Sol-gel involves the hydrolysis and condensation of the titanium alkoxides in aqueous media to produce different morphologies such as aerogels, wires, tubes, quantum dots, sheets, rods, and nanoparticles. ...
... XRD spectra confirmed the formation of different phases of TiO2. The major phases were anatase and rutile [32]. [33]. ...
... Owing to unique optical properties, high thermal and chemical stability and low-level toxicity [1], TiO 2 nanoparticles are being used in photovoltaics, photocatalysis [2][3][4][5], dyesensitized solar cells [6,7], self-cleaning surfaces [8,9], agriculture, anticorrosive and antimicrobial surfaces, air and water treatments [10,11], cosmetics, batteries, sensors and treatment of cancer cells [12]. The much-reported use of TiO 2 nanoparticles as a photocatalyst material is referred to its dominant n-type semiconductor character [13]. ...
In this study, TiO2 nanopowders were prepared by combining the surfactant assisted sol–gel method with microwave plasma calcination. Plasma calcination was performed just for 20–30 min for reducing the calcination time and ensuring the energy efficient synthesis of photocatalyst. The mixed anatase–rutile phased TiO2 nanoparticles were obtained under these synthesis conditions. The band gap energy of the photocatalyst decreased by 40% on microwave plasma calcination. The surfactants were found to be ineffective on phase transformations of synthesized TiO2. FTIR analysis confirmed the absorption of O–Ti–O band stretching between 415 and 420 cm−1. The hydroxyl bands (OH) were observed to be less stretched after plasma calcination. The conventionally calcined HA–Ti, NA–Ti and MS–Ti samples showed band gap energies of 5.09 eV, 4.88 eV and 5.06 eV, respectively. The band gap energy of plasma calcined MTHA–Ti, MTNNA–Ti and MTMS–Ti samples was calculated about 4.92 eV, 3.11 eV and 4.96 eV, respectively. The combined effect of photocatalyst, plasma reactive species and UV radiations promoted the degradation efficiency of the methylene blue dye. Under DC plasma jet exposure, the maximum degradation efficiency of 95% was achieved after 30 min of plasma exposure time. The catalyst retained about 93–95% degradation efficiency after five cycles of dye degradation.
... There exist unique properties in TiO 2 such as; high chemical stability, natural abundance, photoactivity, resistance to chemical corrosion and poisoning, low cost as well as photostability [4,13]. These properties make it suitable for use in self-cleaning surfaces, counter electrode and photoanode in dye-sensitized solar cells [14], pigments to attenuate UV radiations [15], superhydrophobic coating, photocatalysis, sensitizing agent in sonodynamic and photodynamic therapy and as enhancement agents in radiation therapy [16] and water splitting devices [17]. The anatase TiO 2 has been mostly used in solar cells and photocatalysis due to its high photoactivity [13]. ...
This article focuses on the preparation of high-quality titanium dioxide (TiO 2) nanoparticles (NPs) using a simple sol-gel method. The effect of varying concentration of tetra isopropyl orthotitanate (TIP) on the structural and optical properties was examined. Solutions were formed at room temperature and allowed to age, dried at 130 � C into the powder then calcined at 500 � C for 2 h. XRD results confirmed the presence of a mixture of anatase and rutile at all the varied TIP concentration. SEM micrographs showed that the TiO 2 NPs were agglomerated and the morphology was somewhat spongy. The elemental composition and nature of the material were obtained by Energy Dispersive Spectroscopy (EDS) and Fourier-transform infrared spectroscopy (FTIR). UV-Vis spectra showed a blue shift which was an indication that an increase in TIP concentration increased the bandgap and favoured the formation of anatase phase. The optical bandgap obtained using the Kubelka-Munk equation was in the range of 2.7 to 3.12 eV which implied that the photoactivity will take place near visible light. Photo-luminescence spectroscopy (PL) showed that an increase in diameter of the NPs improved the PL intensity. This study reveals a simple method suitable for the synthesis of a mixture of anatase and rutile TiO 2 with desirable optical properties for various applications.
... Synthesis methods take up a significant role in contriving different properties of materials favorable for several applications. A number of synthesis methods such as sol-gel technique (Cenovar et al., 2012;Nachit et al., 2016), hydrothermal/solvothermal approach (Lee and Kale, 2008;Manjunath et al., 2018;Ramakrishnan et al., 2018;Wu et al., 2007;Moa et al., 2019), refluxing (Phonkhokkong et al., 2016), CVD (Guo et al., 2013;Rizal et al., 2015), microwave assisted synthesis (Shen et al., 2015) and electro-deposition (Benea and Danaila, 2017;Patra et al., 2016) have been reported for titania nanoparticles. Among them, solvothermal synthesis has the advantage of making the reactants soluble under high temperature and pressure, which may not be possible with normal reaction conditions, leading to the formation of crystalline nanoparticles without additional heat treatment. ...
Titania nanoparticles with intriguing properties like improved surface area, porosity and excellent transparency have been obtained through solvothermal treatment under a mixed organic solvent medium. The study involves acetic acid and ethanol mixture as the solvent. Contrary to the earlier reports, the resulting nanoparticles are phase pure anatase TiO 2 and maintain the phase even with alterations made in solvent mixture volume ratio. Varying ratios are chosen for studying the influence of acetic acid on the resultant nanoparticles. Surface area and transparency are found to be significantly influenced by the reaction mechanism. Effect of variation of solvent mixture to precursor volume ratio and solvent mixture volume ratio on the size, shape, porosity, surface area, morphology and phase of resultant TiO 2 particles is analyzed in detail. Improved surface area, porosity and transparent nature shown by the synthesized samples compared to commercial anatase titania give an impetus to the photoactive response of TiO 2 nanoparticles. Owing to the superior properties possessed by the synthesized TiO 2 , its photovoltaic behavior as photoanode material is analyzed in DSSC. Distinctly, synthesized titania nanoparticles show enhanced performance (46% increment) than commercial TiO 2 where the high transparency, greater surface area and mesoporosity of the synthesized TiO 2 nanoparticles collectively account for the improved device performance.
... Various methods have been used to preparation of TiO 2 such as chemical vapor deposition (CVD) [24], hydrothermal method [25], hydrolysis [26], atomic layer deposition (ALD) [27], solvent evaporation [28], combustion [29], chemical precipitation [30], pulsed laser deposition technique [31], electrodeposition [32], sol-gel [33,34] and radio frequency sputtering [35]. Since film preparation method may affect the electrical, structural and optical properties of the TiO 2 film or electronic devices, therefore heterojunction device parameters such as ideality factor, barrier height, rectification ratio (RR) may be affected from related method too. ...
The n-TiO2/polyphenylene (PPh)/p-Si heterojunction devices were fabricated in which PPh film and TiO2 top layer were grown on p-Si substrates by diazonium modification method and cathodic electrodeposition, respectively. The XPS, UV–vis diffuse reflectance and STM analyses of the films were performed. After the characterization of deposited films and the fabrications of n-TiO2/PPh/p-Si sandwich devices, the electrical measurements of nine devices were carried out from the current–voltage (I–V) characteristics, at room temperature. The I–V characteristics of n-TiO2/PPh/p-Si heterojunctions were compared with TiO2/p-Si heterojunctions, one of them was analysed in more detailed and it was observed that the n-TiO2/PPh/p-Si gave better performance than TiO2/p-Si heterojunctions such that lower ideality factor, higher rectification ratio and more stable reverse current characteristics. Then, the main device parameters of n-TiO2/PPh/p-Si were compared with many devices reported in literature based on TiO2/p-Si device and TiO2 preparation techniques. Furthermore, the rectification ratio of n-TiO2/PPh/p-Si heterojunction was 9.42 × 10⁵, while it was 5.80 × 10² for TiO2/p-Si heterojunction. Later, the capacitance-voltage (C–V) and conductance-voltage (G-V) measurements of the n-TiO2/PPh/p-Si heterojunction was performed depending on applied frequency and bias and it was observed that the values of capacitance and conductance were found a strongly function of bias voltage.
... In the process of TiO2 synthesis, the shape and crystal structure of the material significantly depends on the raw material used. A number of methods have been used to prepare TiO2 nanoparticle such as sol-gel [10], refluxing [11], chemical precipitation [12], microemulsion [12], hydrothermal reaction [13] and combustion synthesis [14]. Among these techniques, the sol-gel process is currently recognized as one of the most important chemical technique for the synthesis of TiO2 nanoparticles, due to several advantages: low processing temperature, versatile processing, high purity of precursor and high homogeneity of sol-gel products. ...
In this study, titanium dioxide nanoparticles were synthesized for possible application in enhanced oil recovery. Sol-gel method was employed with titanium (IV) isopropoxide as the precursor. The prepared materials were characterized using Powder X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), High-Resolution Transmission electron microscopy (HRTEM) and Brunauer–Emmet–Teller (BET) techniques. Reaction parameter such as calcination temperature was varied during the preparation to obtain the uniform TiO 2 nanoparticles with the smallest particle size and high surface area. The results of study revealed that 400 °C is the optimum calcination temperature in preparing TiO 2 nanoparticles producing the smallest crystallite and particle sizes. XRD results indicated that the nanoparticles have formed anatase phase at 400 °C and achieved low crystallite size of 7.27 nm with the smallest average particle size of 19.53 nm through FESEM and HRTEM observations. BET analysis had achieved the highest surface area 103.64 m ² /g.
... Scanning electron microscopy (SEM) shows the high homogeneity of the commercial P25 TiO 2 sample at the anatase phase with a mean particle size of 21 nm and 35-65 m 2 g −1 BET surface area (Brunauer-Emmett-Teller surface area). The particles are spherical, and the nanoparticles with sizes smaller than 50 nm agglomerate [62,63]. SEM analysis is used to investigate the morphology, crystallinity, and surface area of materials. ...
The photocatalytic degradation and mineralization of commercial solution of 2,4-dichlorophenoxy-acetic acid (2,4-D) was carried out by UVA/P25 TiO 2 and UVA/P25 TiO 2 /H 2 O 2 oxidation processes under batch-mode conditions. In UVA + TiO 2 photocatalysis (TiO 2 1.5 gL ⁻¹ , pH 5, initial 2,4-D 25 mg L ⁻¹ ), 97.47% ± 0.27% degradation, 39.89% ± 3.42% mineralization, and 65.52% ± 4.88% oxidation were achieved in 180 min, and in UVA +TiO 2 + H 2 O 2 photocatalysis (TiO 2 1.5 g L ⁻¹ , pH 5, initial 2,4-D 25 mg L ⁻¹ , H 2 O 2 150 mg L ⁻¹ ), 99.74% ± 0.08% degradation, 55.99% ± 2.67% mineralization, and 82.49% ± 1.90% oxidation were obtained in 180 min. The pseudo-first-order kinetic model fitted the experimental data well, and the photocatalytic degradation process was explained by the modified L–H model; k c and K LH were 1.293 mg L ⁻¹ min ⁻¹ and 0.232 L mg ⁻¹ , respectively. Fourier transform infrared (FTIR) spectroscopy spectra and scanning electron microscopy (SEM) analysis indicated degradation of organic bonds of the herbicide and adsorption of 2,4-D particles onto the TiO 2 catalyst during 24-h experiments. Moreover, the dependence of k app on the half-life time was determined by calculating the electrical energy per order (E EO ). UVA/TiO 2 /H 2 O 2 photocatalysis may be applied as a pretreatment to 2,4-D herbicide wastewater at a pH of 5 for biological treatment.
... The XRD revealed that the sample of TiO 2 NPs was highly crystalline. Broad peaks were observed with high intensity at 2theta scale= 25 [51,52] of titania. The peaks provide evidence to the formation of multi phase (Anatase and rutile) nanotitania. ...
Abstract:
Aim and Objective: Benzodiazepines and indole fused heterocycles are pharmacologically significant scaffolds. Trivial work on indole fused benzodiazepine compounds is reported in the literature. Hence, it is imperative to explore the synthesis of indole-fused benzodiazepines that may act as a template for biological studies in the future. Hence, in the present work, the synthesis of indole fused benzodiazepine derivatives was undertaken using multi-phase nano-titania as catalyst under microwave irradiation. Materials and Methods: MAOS technique was used to carry out the synthesis of spiro-benzo [1,4]diazepine derivatives in the presence of multiphase nano-titania as a catalyst. Nano-titania was prepared by sol-gel method and characterized by XRD, FT-IR, FESEM, EDS and thermogravimetric techniques. The synthesized spiro-benzo [1,4] diazepine derivatives were identified by physical and spectral methods. Results: Synthesized compounds were obtained in excellent yields in a short span of time. The synthesis was also carried out in the presence of conventional catalysts in addition to nano-titania. Among all the catalysts, the best result was obtained with nano-titania. The amount of nano-titania was optimized to be 0.05g giving 93- 95 % yield of products. The study of reusability of nano-titania revealed that it could be reused up to four times with a negligible change in efficiency. Conclusion: The paper reports an efficient, cost-effective and environmentally benign approach for the synthesis of spiro-benzo [1,4] diazepine derivatives in the presence of multiphase nano-titania catalyst under microwave irradiation.
... For the non-doped samples, the curve interpolation appears at 387.5 nm which is the wavelength that corresponds to the anatase band gap energy of 3.2 eV [46]. The UV/Vis absorption spectrum of the usual TiO 2 reference (powder P25 from Evonik) is presented in Fig. 20 as a reference [47]. Comparing this spectrum with those characteristic of deposited non-doped films, it can be noticed that the non-doped thin films (for both powers) present almost the same cut-off as the reference (around 380 nm) which confirms the anatase phase growth by LF-PECVD. ...
A one-step low-frequency Plasma Enhanced Chemical Vapor Deposition (PECVD) process, operating at temperature as low as 350 °C, has been implemented to prepare single-oriented pure and N-doped anatase films. The layers have been synthesized using titanium isopropoxide as a precursor, and NH3 as a doping agent. Optimized PECVD conditions have enabled to obtain homogeneous micro-columnar porous thin films with thicknesses close to 500 nm. Depth profiling XPS analyses have proved the nitrogen incorporation into TiO2 lattice after ammonia introduction in the deposition chamber. As another proof of N-doping, Raman and XRD peaks shifting have been observed. Such thin films have been demonstrated as efficient photocatalytic materials which activity region can be tailored from UV to visible region by adjusting the proportion of doping agent in the plasma phase. Due to their microstructural and photocatalytic properties, the prepared thin layers should have an interest as anode materials in solar water splitting cells.
The catalytic activity of a material highly had been dependent on the nature of the matrix. To address this issue, a detailed study was aimed. TiO2 nanoparticles were fabricated with an unusual anatase crystal phase and an interesting porous morphology. The development of porosity in TiO2 was skillfully achieved by using hexamine during the synthesis, followed by its selective removal by calcination at an optimum temperature. The route was found to be template‐free, green and thoroughly reproducible. Surface of the as prepared TiO2 was modified with oleic acid expecting an interaction between Lewis acidic TiO2 and electron rich oleic acid. This modification enabled adhesion of Ag nanoparticles on TiO2 surface, since oleic acid had already been reported as an effective capping agent for Ag nanoparticles. A comparison was made between the photocatalytic activities of TiO2 and TiO2‐Ag nanocomposites. This was further compared with commercial variety of TiO2. A very interesting trend was observed establishing that porous morphology of the nanoparticles could boost photocatalytic activities towards dye degradation in water medium. All the samples were systematically characterized by FTIR, XRD, XPS, BET and TEM.
This review highlights and summarizes the impact of different fabrication processes on the efficiency of dye-sensitized solar cells (DSSCs). Energy conversion efficiency of cell depends upon semiconductor, sensitizer, electrolyte, and counter electrode. Efficiency of DSSCs can be enhanced by properly selecting the optimum significance of various parameters of fabrications process. Major challenges of these solar cells are non-vegetal, noxious, extreme sensitizers. Application of natural dyes in this field plays a significant role. An optimized CdSe-TiO2 photoanode showed a power conversion efficiency (PCE) of 13.29% and short circuit current density of 15.30 mA cm⁻² for the DSSC. Power conversion efficiency of 3.26% was achieved by using TTO electrode for DSSC device that is ascribed to the improved electrical and optical properties due to doping with Ta element. Absorbance of betalain was shown in the visible range of 530–535 nm for betanin while 450–559 nm for anthocyanin pigment. The natural dyes are economical, readily available, and environmentally friendly. This compilation would be beneficial for researchers working on dye solar cell.
This article focuses on the preparation of high-quality titanium dioxide (TiO2) nanoparticles (NPs) using a simple sol-gel method. The effect of varying concentration of tetra isopropyl orthotitanate (TIP) on the structural and optical properties was examined. Solutions were formed at room temperature and allowed to age, dried at 130 °C into the powder then calcined at 500 °C for 2 h. XRD results confirmed the presence of a mixture of anatase and rutile at all the varied TIP concentration. SEM micrographs showed that the TiO2 NPs were agglomerated and the morphology was somewhat spongy. The elemental composition and nature of the material were obtained by Energy Dispersive Spectroscopy (EDS) and Fourier -transform infrared spectroscopy (FTIR). UV–Vis spectra showed a blue shift which was an indication that an increase in TIP concentration increased the bandgap and favoured the formation of anatase phase. The optical bandgap obtained using the Kubelka -Munk equation was in the range of 2.7 to 3.12 eV which implied that the photoactivity will take place near visible light. Photoluminescence spectroscopy (PL) showed that an increase in diameter of the NPs improved the PL intensity. This study reveals a simple method suitable for the synthesis of a mixture of anatase and rutile TiO2 with desirable optical properties for various applications.
Increase in industrial and anthropogenic activities leads to a decline in water quality. This necessitates the need for the removal of contaminants from industrial and domestic wastewater. Clay minerals are naturally abundant and non-toxic materials that found to be useful for remediation of emerging contaminants from wastewater. This review paper presents an insight into clay, the simplest material (in solgel techniques) for the synthesis of TiO2 and ZnO, mechanisms of their reactions, analytical techniques used for characterizations, and their nanocomposites for wastewater treatment. Nanomaterials, such as nanoclay, titanium, and zinc oxide, have offered the opportunities of sequestering variety of pollutants in wastewater. TiO2 and ZnO anchored on clay have been found to be good promising sequesters and have been explored for wastewater remediation via nanotechnology. This water treatment method includes adsorption/absorption, photocatalysis, and microbial disinfection. These nanocomposites provide more active surface sites and reduce the agglomeration of the nanoparticles, but leaching has been their shortcomings. To overcome this, the filtration technique may become significant for the removal and avoidance of fouling of wastewater. This can be achieved through the fabrication of nano-based filters using the nanocomposites.
The access of dye-sensitized solar cells (DSSCs) in the photovoltaic market is still a challenge owing to low power-conversion-efficiency (PCE) and stability. The foremost aim of this review is to emphasize the technical issues in DSSCs that reduce their efficiency. A DSSC consists of glass substrates, photoanode, photosensitizer, electrolyte and catalytic counter-electrode. Electrode materials play a critical role in the photovoltaic (PV) performance of DSSCs. The PV performance of DSSCs depends on many factors e.g. electron collection at photoanode, light harvesting efficiency of photoanode, a scattering of electrons inside the photoanode, and the fast reduction of an electrolyte at the counter electrode. In this review, physical, electronic, and morphological properties of electrodes materials will be examined for efficient DSSCs. This review paper comprises of four parts. First part highlights the importance, structure and charge transport mechanism of DSSCs. The second section describes the types, electronic and morphological properties of photoanode materials. The third part covers the nature and catalytic properties of materials used for counter-electrodes. Finally, challenges, market and future directions of DSSCs will be described in the last part of this review.
The existence of zircon (ZrSiO4) in the nature is mostly associated with some of the valuable oxide compounds (VOC), such as TiO2 and rare earth oxides (REO). The existence of natural minerals in Indonesia containing zirconium (Zr) and REO lies in 13 regions, ranging from Aceh to West Papua province. Based on those aforementioned aspects, the goal of this research is to conduct the study of integrated technology of local zircon sand processing containing TiO2 and REO. The study was conducted by analyzing the content of VOC in zircon sand samples from the areas of Landak and Tumbang Titi West Kalimantan and Bangka by using XRF. Based on the content of VOC in this zircon sand, it can be predicted that the zircon sand from the area of Landak and Tumbang Titi West Kalimantan and Bangka contains mineral zircon (ZrSiO4), ilmenite (FeTiO3), monazite (LREE, Th)PO4, and xenotime (HREE, Th)PO4. Based on these types of mineral, the flow chart of beneficiation technology process to increase the concentration of each mineral and the flow chart of zircon concentrate process into ZrO2(zirconia) and ZrOCl2.8H2O (zirconium oxychloride) industrial grade and zirconia and zirconium chemicals nuclear grade, ilmenite into TiO2, monazite into Nd2O3, and Th(OH)4 concentrate, xenotime into Y2O3, Gd2O3, and Th(OH)4 concentrate are obtained in one area of pilot plant or an integrated factory. The results of the study concluded that the concept of local processing of zircon sands containing monazite, xenotime, and ilmenite can be either integrated in the region with the results of multi-product plant. If it can be realized in Indonesia with the addition of an integrated waste water treatment system, then in addition to safe for the environment can also save on production costs and give economic added value for shareholders zircon mining permit
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